Gas burners are commonly used on the cooktops of household gas cooking appliances including e.g., range ovens and cooktops built into cabinetry. A significant factor of gas burners is their ability to withstand airflow disturbances in the surroundings, such as room drafts, rapid movement of cabinet doors, and most commonly oven door manipulation. For appliances which include both an oven and cooktop, manipulation of the oven door can be particularly troublesome because rapid opening and closing of the oven door can produce respective under-pressure and over-pressure conditions within the oven cavity. These pressure changes may cause rapid expansion and/or contractions in the structures. As a result, a large amount of air passes through or around the gas burners with e.g., rapid opening or closing of the oven door(s). Similarly for built-in cooktops, pressure changes due to rapid manipulation of surrounding cabinets may result in large amounts of airflow through or around the gas burners.
Such surges of air around the gas burners, due to pressure disturbances in the surroundings, are detrimental to the flame stability of the burners and may cause extinction of the flames. This flame stability problem is particularly evident in sealed gas burner arrangements, which lack an opening in the cooktop surface around the base of the burner so as to prevent spills from entering the area beneath the cooktop.
The inherent cause of this flame instability is the low pressure drop of the fuel/air mixture passing through the flame ports of a typical burner used on the cooktop of an appliance. Although there is ample pressure available in the fuel, the pressure energy is used to accelerate the fuel to the high injection velocity required for primary air entrainment. Relatively little of this pressure is available at the flame ports. A low pressure drop across the flame ports allows pressure disturbances propagating through the ambient to easily pass through the flame ports, momentarily drawing the flame towards the burner base and leading to thermal quenching and extinction.
A solution to the above-described problem is the use of a stability chamber as described e.g., in U.S. Pat. No. 5,800,159, commonly owned by the assignee of the present disclosure. The burner is able to maintain a simmer flame at both low and high settings so that the simmer flame can relight the flame at primary flame ports when needed. However, the use of stability chambers has been limited to gas burners having a centrally located burner throat that delivers fuel to the flame ports in a radially outward fashion. Thus, inwardly fired burners, such as inverted gas burners, cannot withstand pressure disturbances as well as traditional gas burners, and are more prone to flame extinction due to pressure disturbances.
Accordingly, an inwardly fired burner with features for maintaining a simmer flame would be welcomed within the technology.